After four months, the study found there was almost no difference in fitness gains between the three groups. However, those who exercised four times a week expended more energy and burned more calories per workout than those in both other groups. Those who worked out twice a week increased their calorie burn and energy.

Those who exercised the most expended considerably less energy per workout than at the study’s start, and burned less calories.

The women who exercised the most complained it took too much time and in reaction were more prone to drive instead of walk and opt for the elevator rather than stairs to save time, reports the Times.

The weekly workouts were divided evenly between strength training and cardiovascular exercise. The weekly two-timers did one day of strength and one day of moderate cardiovascular, the weekly four-timers did two days of each, and so on.

The study did not focus on weight loss and the women were not asked to change their eating habits. Rather, researchers at the University of Alabama, where it was conducted, focused on health benefits such as improved endurance, calories burned and strength.

“If you’re more intense with your exercise and if you’re focused, four days may be enough,” says WTOP’s fitness trainer Fairfax Hackley, who added that workouts should include three vital parts, including cardiovascular, strength training and flexibility.

“If you don’t have a balance, everything is grind, grind, grind. It’s just like a razor or a knife, you can only sharpen it so much.”